Ever higher requirements are imposed on an internal combustion engine, such as an engine of a motor vehicle, with a view to reducing the consumption of fuel and the generated exhaust gas while, at the same time, providing increased power. To satisfy these requirements, it is necessary that all components of the engine operate with continued precision and that even slight changes and defects are detected early and reliably.
Modern internal combustion engines are provided with a fuel supply system wherein the supply of fuel into the combustion chamber of the engine is carried out electrically and especially with a computer-supported control apparatus. It is possible to inject the fuel into an air intake manifold of the fuel supply system or directly into the combustion chamber of the engine. In the last-mentioned type, it is necessary that the fuel be injected into the combustion chamber under pressure. For this purpose, a pressure store is provided into which the fuel is supplied by means of a pump and is placed under pressure. From the pressure store, the fuel is then injected via injection valves into the combustion chambers of the engine.
For a precise control (open-loop and/or closed-loop) of the injected fuel quantity, the pressure store is provided with a pressure sensor with which the pressure in the pressure store is measured. The pressure valve and/or the pump are so controlled (open-loop and/or closed-loop) in dependence upon the measured pressure that a desired pressure is provided in the pressure store. An imprecise measurement of the pressure by the pressure sensor or even a defect of the pressure sensor can have as a result that the desired pressure cannot be provided and therefore the initially-mentioned requirements of the engine can no longer be satisfied.